I've read a lot of threads where others are talking about Zimbra server performance on ESX/ESXi, but my experience tells me it is confusing.

For example, I have one Zimbra 8.0.2 server on Ubuntu 10.04, running on ESXi 5.0.
ZCS has 8 GB dedicated RAM, and 2GHz reserved and available all 10GHz total power of host, which runs on 2 x Quad XEON 2,5 GHz.
It is single-server all-in-one Zimbra installation, with 400 mailboxes.

Average MTA digestion is approx. 9.000 email messages per day, except a spike of 10.000 up to 100.000 mails sent out by some mailing outburst once per day or two.

Average CPU usage is 7%...
...but during these mailings, where single user sends mail out to 10.000 or sometimes even to 100.000 users, CPU of total host burns oil at 80-100% and chokes the whole ESXi server.

Is such a behavior normal?
Well, I know the mailing application does NOT send 1 single mail with 100.000 recipients, but rather sends out 1-by-1, single mail at the time, so there is really huge traffic. But should that choke my whole ESXi? It becomes unresponsive, mail queues extend to 1000 or more mails in Queue, mail delay is up to 4 hours, and web sites, which are also run at this ESXi, return "Timeout".

What hardware upgrade would help most?
Is it RAM upgrade?
Or should Ultra fast SSD PCI-e adapter ioDrive from Fusion boost performance?
Or should I replace SATA disks in RAID 10 with faster SAS 15k disks?

Ideas welcome.

02-23-2013, 07:25 AM

lytledd

Similar setup to yours. Quad core Xenon, ESXi 5.0, dual 15k SCSI drives and around 300 users. The differences are, our outbound for a single mailing usually only hits a couple thousand at once. My VM is also Ubuntu 10.04 LTS, but /opt/ is on a LVM and I don't use RAID at all.

My suggestions would be to:

Disable swap, our VM is using 9GB without swap, but I have 27GB assigned. To date, it hasn't gone above 9.
If you're able, get rid of RAID.

Well, thanx for advice...which I agre with mostly, except on the part "Get rid of RAID", which is misleading. If we are talking about RAID 5 or 6 type, yes, then it is true - these RAID types are not the performers, but rather optimized for capacity. While on the other hand RAID 1, 10 and even RAID DP are optimized for performance (RAID DP also +capacity) and ARE recommended much more than single-disk operation, be it performance-wise or security-wise.

Now back to my problems.
What bothers me most is understanding the SWAP. I know, there are TWO SWAP layers in my config:
- Zimbra OS SWAP inside virtual machine, swapping to virtual disk
- and ESXi host swapping consumed VM RAM to ESXi host disk

Regarding ESXi SWAP I have all sorted out, I monitor ESX swap all the time and act immediately. Most of the time none of my VM swap, but as I have 2 VMs without proper VMWare Tools, it happens every 2-3 weeks that one of machines begins swapping. I reboot them ASAP to get rid of swap.

While internal OS SWAP... well, my Zimbra shows the following (sorted by SWAP):

First... how come "slapd" process using 80G of swap and only 0.7% of RAM??!! Where I missed the point?
Secondly... are these numbers telling me, that my Zimbra is crying for more RAM?

02-24-2013, 05:11 AM

ccelis5215

Hi Labsy,

Quote:

First... how come "slapd" process using 80G of swap and only 0.7% of RAM??!! Where I missed the point?
Secondly... are these numbers telling me, that my Zimbra is crying for more RAM?

Regarding your first question, this columns show the maximum amount of swap will be required if the whole process was swapped out,
and yes..., maybe you need more RAM.

I know, this answer it's not very helpful.

ccelis

02-24-2013, 09:18 AM

lytledd

I've never done anything beyond RAID 5.

As for the swapping, I've noted that if it's enabled, Zimbra will use it, even if there is plenty of memory. That's why I initially gave the VM 27GB. It's settled around 9GB.

Also worth noting, We've been using ASSP for spam filtering and virus scanning for years, before we moved to Zimbra. So, that portion of Zimbra has been disabled for us since the beginning.

Doug

02-24-2013, 02:36 PM

Labsy

Hmmm...
So, here's what crosses my mind:

1.) Would it be wise to disable swapping on Zimbra OS-level while at the same time doubling RAM from 8 to 16 GB?
...or should just change "swappiness" for Linux from default 60 to, let's say, 10 or even 0?

2.) We are using our own ASF Antispam for the most important 1/4 domains (business users), so Zimbra is not under pressure. But still it has Antispam and Antivirus enabled for the rest 3/4 of domains.

02-24-2013, 03:18 PM

ccelis5215

Hi again,

Quote:

Originally Posted by Labsy

1.) Would it be wise to disable swapping on Zimbra OS-level while at the same time doubling RAM from 8 to 16 GB?
...or should just change "swappiness" for Linux from default 60 to, let's say, 10 or even 0?

No, it's not wise disable swap in a complex application server as Zimbra.
16 GB will be better than 8.
Yes, turn swappiness to 0

ccelis

02-24-2013, 04:33 PM

lytledd

I also agree with ccelis,

16GB and swappiness=0

You can keep an eye on it for a couple weeks to get an idea what it'll actually be using, then you can lower it if necessary. I've left mine at 27GB, since it's the only VM on the machine.